Typically, air traffic control bodies can require aircraft to pass given points of the airspace at given times, or RTAs according to the initials of the expression “Requested Time of Arrival” for a planned time constraint or CTA, according to the initials of the expression “Controlled Time of Arrival” for a time constraint activated by the air traffic controller. Hereinafter, these two types of constraints will be designated RTA without distinction.
During flight preparation or during rerouting, the crew input various items of information relating to the progress of the flight, typically by using an aircraft's flight management device, commonly designated by the acronym FMS, corresponding to the expression “Flight Management System”. An FMS comprises input means and display means, as well as computation means, and an operator, for example the pilot or the copilot, can input via the input means information such as RTAs, associated with waypoints, that is to say points vertically in line with which the aircraft must pass.
The computation means make it possible notably to compute, on the basis of the defined flight plan, that is to say on the basis of the list of waypoints, the trajectory of the aircraft, as a function of the geometry between the waypoints and/or the altitude and speed conditions, used notably for computing the turning radii. Over the lateral trajectory thus determined, the computation means are also configured to optimize a vertical trajectory, employing possible altitude, speed and time constraints.
The input of the information, and the display of the information which is input or computed by the display means, constitute a man-machine interface or “MMI”.
With known devices of FMS type, when the operator inputs a waypoint, he does so via a dedicated display displayed by the display means. This display may optionally also display information relating to the temporal situation of the aircraft in relation to the waypoint considered. The operator can then input and view a time constraint imposed for this waypoint. An example display of the information relating to a waypoint, in a device known from the prior art, is illustrated by FIG. 2, described in detail hereinafter.
However, flights may involve multiple RTAs, that is to say several waypoints may be associated with various time constraints. With the known devices of FMS type, the management of constraints of multiple RTA type is tricky or indeed impossible: though it is sometimes possible to insert several time constraints into a flight plan, the operator can input and view the information relating to a single waypoint, and must request the display of various screens to view and input, if appropriate, the information specific to as many different waypoints. Modifications made to the constraints relating to a given waypoint do not impact the temporal situations specific to the other waypoints of the flight plan, and it is necessary for the pilot to indulge in irksome and protracted gymnastics by manually swapping the display of the various screens specific to the various waypoints of the flight plan considered, and by determining, mentally or with the aid of remote computation devices, what may be the implications of modifications to constraints on a given waypoint, in relation to the other waypoints of the flight plan.